Thank you for replying, but after doing some more researching and testing, I’ve come to the conclusion that FiveM doesn’t fully support streaming of the vehicles.meta for replacement of stock vehicles.
The gameName was different between the two entries, but that should not affect the handling because gameName corresponds to the text that appears when entering a vehicle. Anyways, an interesting note you brought up about that… I tried replacing the gameName for another stock vehicle (Ambulance). The Ambulance also has this handling issue where I assigned the YOUGA2 handling in vehicles.meta, but FiveM doesn’t detect this, having my Ambulance tip over at any sharp turn… Anyways back to the gameName, I changed it but FiveM still displays the Ambulance gamename.
All of that ^ along with the engine audio being incorrect, and some of the interior dashboards not displaying correctly for replacement vehicles, all leads to vehicles.meta where these are assigned.
Also, the people below had the same issue:
However, I believe FiveM does support all changes to handling.meta. So a half-way solution to this would be replacing the handling of the stock vehicle, in handling.meta.
This will fix most of the handling, but all flags from the original vehicles.meta entry will remain, the engine audio, the dashboard interior, the vehicle name, etc.